中文摘要：

[目的]粮食安全问题是政府必须首先解决的问题。在中国人口急增、消费扩张、耕地大幅度减少的现状下，分析中国的粮食安全保障问题。【方法】利用经验模态（EMD）方法分别对1949—2006年问中国粮食产量及耕地面积波动进行多时间尺度分析，并构建动力学模型进行预测，分别从粮食的趋势产量和耕地变化的粮食供给量两方面分别与基于人口发展的粮食需求量进行比较。【结果】①新中国成立以来中国粮食产量以9．6年准周期波动为主；耕地总量以14．5年准周期波动为主。②若以每10年增加1×10^8t左右粮食的生产能力增长，中国粮食的趋势产量能够满足至2030年中期内人口发展的消费需求，但进一步提高人均粮食占有水平的空间极为有限。③从耕地发展看，只要粮食单产达到预期目标，可以满足2030年人口的消费需求，但耕地资源的承载压力日益增大，超载人口数量持续增加。[结论]中国未来的粮食安全保障前景令人担忧。中国必须严格控制人口数量、增加后备耕地数量、努力提高土地质量以及提高粮食单产，才能缓解中长期粮食的供需矛盾。

英文摘要：

[ Objective ] Grain security problem is the first importance for our government to solve. The rapid increase of future population and food consumption coupled with a decrease of total cultivated land at a rather greater speed in recent years will badly affect the safety of grain security in our country. [Method] In this paper, Empirical Mode Decomposition （EMD） method was introduced to study the fluctuation of grain output and cultivated land and their causes at multi-time scale from 1949 to 2006, then a dynamical model is established to predict the grain tendency production and cultivated land change in the next 30 years, through which the future grain security based on population development and cultivated land change was analyzed. [Result] The results of study are as follows： （1） The fluctuations of grain output have 3.6-year, 9.6-year and 14.5-year time scales and fluctuation of the 9.6-year time scale is more prominent. Cultivated land mainly has a 14.5-year time scale. （2） Shown from the residual trend term of grain output, fill the people-estimated peak of population of 2030, the grain output can satisfy the requirement of 1.49 billion people at a per capita consumption of 400-470 kg grain. However, grain output of 10^10 kg every ten years should be increased and a great effort should be made and to expand the potentials of grain production, which will be disadvantageous to the sustainable development of future agriculture. （3） Shown from the residual trend term of cultivated land, when the productivity per hectare increased to 5008-5133, 5598-5798 and 6439-6725 kg in 2010, 2020 and 2030, and the same proportion of grain planting is always kept, the grain production based on cultivated land can absolutely ensure 95% self-sufficiency goal brought forward by the white book 《Food Issue in China》 . However, further increase in per capita grain occupancy is not optimistic, due to the restriction of limited arable cultivated land resources. [ Conclusion] The foreground of future grain secur